Aluminium alloy



Patented Aug. 16, 1932 UNITED STATES PATENT OFFICES- EOBACE CAMPBELLHALL, OF LITTLEOYER DERBY, AND TENNYSON FRASER BRAD- BURY, OF DERBY,ENGLAND, ASSIGNORS '10 ROLLS ROYCE LIMITED, OF DERBY,

I ENGLAND ALUMINIUM ALLOY No Drawing. Application filed October 16,1930, Serial No. 489,224, and in Great Britain October 24,1929.

It is common knowledge that aluminium and aluminium alloys are liable tocorrosion when exposed to the air.

The object of this inventionis to make a light aluminium alloy having ahigher resistance to corrosionthan any such alloy previously known whichcan be satisfactorily cast, forged or extruded, and this withoutsacrificing hardness and strength orby sacrificing but little of thesequalities.

According to this invention we make an alloy by compounding the elementsand that in the relative quantlties within the ranges set out below.

Magnesium'from 0.1 to 4 per cent of the whole.

Nickel from 0.5 to 2.5 per cent of the whole.

"Iron from 0.3 to 1.5 per cent of the whole.

Silicon from 0.5 to 5.0 per cent of the whole.

Titanium up to 0.5 per cent of the whole.

anganese up to 0.2 per cent of the whole.

Chromium from .01 to 0.2 per cent of the whole.

Copper up to 0.5 per centof the whole.

Aluminium the remainder except for traces only of other elements.

An alloy compounded as above has a greater resistance to corrosion thanfor example, that claimed in our application for Letters Patent No.401,970 now United States Patent No. 1,7 82,300 but at the sametimepossesses about 80 per cent of the hardness and strength of thatalloy.

Further this alloy has a higher resistance to corrosion than anypreviously known light allo of aluminium that it is possible to cast toorce and to extrude satisfactorily due largely to the presence ofchromium and to the small copper content associated with the chromium,it is lighter than the aluminium alloys commonly in use which containcopper or zinc with or without other constituents, it

so The alloy is made in manner common in is capable of being cast,forged or extruded foundry practice, that is to say,'to moltencommercial aluminium are added alloys rich in one or more of the otherconstituents other than magnesium, which is last added in the metallicstate.

Preferably the alloy is cleaned and deoxidised prior to being cast bythe addition of sodium. Such sodium may be added by wrapping a piece ofmetallic sodium (preferably) not exceeding- 0.1 per cent of the alloy tobe treated in a piece of sheet aluminium or aluminium foil the wholebeing plunged below and held below the surface of the molten alloy untilthe sodium is diffused.

What we claim is V f 'An aluminium alloy formed by compounding theelements and that in the relative quan- Igitlies respectively within theranges set out e ow 1lllagnesium from 0.1 to 0.4 per cent of the w ole.Nickel from 0.5 to 2.5 per cent of the whole.

Iron from 0.3 to 1.5 per cent of the whole.

Silicon from 0.5 to 5 per cent of the whole.

Titanium up to 0.5 per cent of the whole.

Manganese up to 0.2 per cent of the whole.

Chromium from ;01 to 0.2 per cent of the whole.

Copper up to 0.5 per cent of the whole.

Aluminium the remainder except for traces only of other elements,

In testimony whereof we have hereto affixed our signatures.

HORACE CAMPBELL HALL.

TENNYSON FRASER BRADBURY. 7

